A New Construction of Identity-Based Signcryption without Random Oracles

The concept of signcryption, introduced to the public by Zheng [19], is a primitive that combines the functions of both digital signature and public key encryption. The efficiency of signcryption is higher than sequential composition of digital signature and public key encryption. Identity-based signcryption is a specific type of signcryption, in which each user’s public key can be a string identifying this user (e.g. an e-mail address, a telephone number, etc.). This eliminates the need for certificates as used in a traditional public key infrastructure.